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POHow to reference ID property in relationship with NHibernate?
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How do I map relationship, where child endpoint is exposed via Id property and not via whole Parent object? Here is the example: <pre><code>class Parent { public Guid Id { get; set; } public List<Child> Chlidren { get; set; } } class Child { public Guid Id { get; set; } public Guid ParentId { get; set; } } </code></pre> Here are the equivalent mappings I'm using: <pre><code><?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="Blabla" namespace="Blabla" auto-import="false"> <typedef name="ChildrenList" class="Blabla" /> <class name="Parent" table="Parent" lazy="false"> <id name="Id" column="ID" type="Guid"> <generator class="guid" /> </id> <bag name="Children" table="Child" cascade="save-update" collection-type="ChildrenList" lazy="false"> <key column="ParentID" not-null="true" /> <one-to-many class="Child" /> </bag> </class> <class name="Child" table="Child" lazy="false"> <id name="Id" column="ID" type="Guid"> <generator class="guid" /> </id>  </class> </hibernate-mapping> </code></pre> When I create a parent, add some children to <code>Children</code> collection and then save the parent, everything is fine. But if save a parent object first, then create a child, setting its ParentID property to ID of the parent, then I get <pre><code>NHibernate.PropertyValueException: not-null property references a null or transient value Child._Parent.ChildrenBackref </code></pre> All attempts to map <code>many-to-one</code> relationship resulted in different exceptions while creating NHibernate configuration. Mostly about object type mismatch. I'm sure NHibernate is capable to handle this scenario. There must something fairly basic that I miss. EDIT: I think it make sense to the example test, which fails with above exception: <pre><code>var child = new Child(Create.Saved<Parent>().Id); // this sets the ParentId property this.Repository.Save(child); // here I get the exception </code></pre> My thoughts why NHibernate is raising this: <code>Children</code> property of <code>Parent</code> class mapped in a way that says that a child cannot exist without a parent (<code><key column="ParentID" not-null="true" /></code>). When I try to persist a child, NHibernate tries to resolve this relationship (to find a parent this child relates to) and fails, since being given no child endpoint (which otherwise would be <code>ParentId</code> property) in the mapping, it check for its own <code>Child._Parent.ChildrenBackref</code> endpoint, whatever it is. This looks like a desired solution: Mapping <code>ParentId</code> property as child endpoint of the relationship. This would force NHibernate to resolve a parent by using value of <code>ParentId</code> property as parent's primary key. The thing is I don't know if it's possible.
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<nhibernate><mapping><parent-child><foreign-key-relationship>
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How to reference ID property in relationship with NHibernate?
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